The present invention relates generally to fiber packaging, and more particularly, to compacting and packaging fibers into a bag for mixing into concrete.
Synthetic fibers of all types are commonly cut into short and/or random lengths for use as secondary reinforcement in concrete or cement based structures. The fibers are typically packaged in paper bags that can be placed directly into a concrete ready mix truck, a central batch plant, or another mixer for distribution throughout concrete or the like. The combined mixing action of the mixer blades and concrete materials such as cement, sand, water, and/or aggregate contributes to a physical deterioration of the bag. As the bag breaks down the fibers are then distributed by the mixing action into the concrete.
Fiber-reinforced concrete made with these bagged fibers sometimes has problems attributable to inadequate or non-uniform mixing and dispersion of the fibers in the concrete. The bags are typically made of a heavyweight paper such as 30 lb. paper to produce a strong and thick package to hold the fibers contained therein.
Such bulky bags are slow to break down in the mixer because they merely flop around in the mixer until they get wet enough to break down. This prolonged mixing operation wastes time and energy. When the bags have become sufficiently saturated to break down, most of the mixing cycle is completed, thus leaving the fibers undistributed and clumpy. The end result can be a concrete structure with fibers that are not uniformly distributed in all directions, thereby producing a secondary reinforcement system that is ineffective for shrinkage crack control in the concrete.
Several techniques have been and/or are currently being employed for packaging fibers into bags, none of which adequately solves the above-described problems. The simplest technique is a manual bagging operation where individuals place the fibers in plastic bags, weigh the contents, make adjustments to the fiber content until a desired weight is achieved, and heat seal the bag. The plastic bags have to be torn open manually before the contents are placed into the truck or central mixer for dispersion.
An improvement to this manual operation has been developed that utilizes form, fill and seal equipment. This equipment allows for a paper bag to be formed, pre-weighed fibers placed inside the bag, and the bag sealed, all in one continuous operation. This is an automatic system and improves accuracy and productivity. However, even with this improved system, relatively large, thick, and heavy bags are required to hold the volume of fibers typically desired.
Additionally, several techniques are known to have been attempted for packaging fibers into lighter weight bags, none of which has been successful or practical in addressing the above-described problems. Difficulties arise in attempting to package the fibers in a lightweight paper bag that breaks down more quickly in the mixer, while also providing a compact package as is desired for efficient storage and transport, easy handling, automatic batching, and easy distribution into the concrete.
Attempted solutions are known to have included modified bulk handling equipment with blowers, bag dispensers, and other bagging concepts such as multiple bags that are linked together like sausages. These attempts have been unsuccessful or the final product too expensive to be practical in the industry. The major problem with such bulk dispensing equipment is that the synthetic fibers are very difficult to handle. The fibers have a natural tendency to bridge, thus blocking the feed mechanism, clogging up the system, and shutting down the equipment. Furthermore, attempting to compact fibers into lighter weight bags has proved difficult because the lightweight bags tend to burst during the packaging process.
An example of known bulk handling equipment is provided by U.S. Pat. No. 5,074,101 to Rewitzer, which discloses a process and apparatus for packaging and pressing loose fibers comprising a fill shaft with distributing and clearing means such as a pivotal trunk, flap, or paddle and screw conveyors. The fill shaft is connected to a rectangular press container having box bag lined therewithin for holding the loose fibers which are then compressed by a press ram. Another known bulk handling system is provided by U.S. Pat. No. 5,623,811 to Hirschek et al., which discloses a process and device for packaging and supplying fiber material comprising a container for fiber material, a hopper and fill device connected to the container, and a press ram for compacting the fiber therein. Neither Rewitzer nor Hirschek et al. provide for compacting fibers into a lightweight bag to overcome the aforementioned problems.
There is also known the device of U.S. Pat. No. 4,004,398 to Larsson et al., which discloses equipment for packaging pulverized material such a coffee in a flexible film container made of foil or plastic. The equipment comprises a firm container around which the film is formed into the flexible container. A table supports the containers and is raised and lowered. A piston moves up and down in the firm container for compacting the material. Larsson et al. does not provide a device suitable for bulk packaging of fibers in lightweight paper bags.
Accordingly, what is needed but not found in the prior art is an apparatus and method for packaging fibers in a bag in which the fibers are handled without clumping and clogging the handling equipment and the fibers are compacted into the bag without bursting the bag, and the bagged fiber article produced thereby in which the bag is capable of breaking down quickly and easily in the mixer to produce a uniform distribution of the fibers in the concrete.
Generally described, the present invention provides an apparatus for packaging fibers in a bag, comprising at least one base plate and at least one fill tube having a lower section, a middle section, and an upper section. The lower section of the fill tube has a bottom spaced apart from the base plate so that the bag may be placed between the bottom of the lower section and the base plate.
At least one bag liner tube is slidably coupled to the lower section so that the bag liner tube may slide between an up position and a down position. The up position provides the bag liner spaced apart from the base plate so that the bag may be placed between the bag liner and the base plate. The down position provides the bag liner generally adjacent to the base plate.
At least one ram slides within the fill tube between an up position within the upper section and a down position within the middle and lower sections. At least one feed tube is attached to the middle section, and at least one distribution bin is attached to the feed tube. At least one rotating pin assembly may be provided in the distribution bin, and an electric control may be provided for the rotating pin assembly wherein loose fibers may be advanced through the distribution bin at a uniform rate.
The bag is positioned over the bag liner tube so that the bag liner tube absorbs the sidewall forces and the base plate absorbs the bottom wall forces resulting from compacting the fibers therein. The bag itself is therefore not subjected to these temporary maximum forces so that the fibers can be compacted therein without the bag bursting.
The method of the present invention generally comprises the acts of mounting a bag over a bag liner tube that is in an up position relative to a lower section of a fill tube, sliding the bag liner tube to a down position such that the bag liner tube is adjacent a base plate, advancing a predetermined volume of loose fibers into a middle section and a lower section of the fill tube while a ram is in an up position within an upper section of the fill tube, sliding a ram to a down position in the bag liner tube and bag wherein the loose fibers are compacted into the bag liner tube and bag, sliding the bag liner tube to the up position relative to the lower section of the fill tube, sliding the ram to the up position within the upper section of a fill tube removing the bag from the bag inner tube, and sealing the compacted fibers in the bag.
The act of advancing the loose fibers may comprise rotating pins in a distribution bin attached to a feed tube attached to the middle section of the fill tube. The acts may be repeated as desired for mass production of bags of compacted fibers. The present invention also provides an article produced by the above-described method, comprising a bag of compacted fibers.